Long‐Term Individual‐Based Monitoring in Bat Conservation: Insights From Automated PIT ‐Tag Monitoring

Background The importance of long‐term, individual‐based field studies in answering key conservation questions is widely recognised. However, such studies are rare in bats due to the challenges involved. Aims This review summarises current knowledge on the outcomes of long‐term, individual‐based monitoring for bat conservation, focusing on data generated by automated passive integrated transponder (PIT) tag monitoring. Methods We reviewed the literature on long‐term, individual‐based bat monitoring studies for conservation purposes, focusing on automated PIT‐tag monitoring. We performed targeted literature searches on statistical tools for analysing individual‐based data collected using automated systems, and on the challenges and opportunities associated with these methods. Finally, we present two case studies, using information from our own long‐term automated PIT‐tag monitoring of five bat species in Germany. Results We found that only a limited number of bat species were monitored using automatic PIT‐tag loggers for more than 3 years. Almost all of these species are temperate‐zone bats. Monitoring was performed at summer roosts, including buildings, caves, bat boxes and tree cavities, as well as hibernacula. The respective studies investigated various conservation‐relevant variables, including movement between roosts, demographic parameters such as survival and reproduction, and population trends. Our own research demonstrates how this method can provide conservation‐relevant information that would not have been obtained using count data or classical capture‐mark‐recapture techniques, which require regular handling of bats. Conclusions Long‐term, individual‐based monitoring remains challenging and resource‐intensive. Automated PIT‐tag monitoring offers new possibilities for long‐term bat monitoring by facilitating the collection of highly relevant conservation data.